The Poranis system is a star system located in either the Alpha or Beta Quadrants of the galaxy. (Ship Recognition Manual, Volume 4: Starships of the Original Series Era)
In 2285, the USS Lysander discovered that the system was a rich source of dilithium. Following the discovery there was a brief skirmish between the Lysander and a Klingon B'rel-class Bird-of-Prey in the system.